The Importance of History for Modern Climate Adaptation Strategies. MENNE KOSIAN , Cultural Heritage Agency of the Netherlands, the Netherlands ROWIN van LANEN, Cultural Heritage Agency of the Netherlands, the Netherlands The Netherlands form a part of the northwest European river delta, where almost all the major European rivers drain onto. Therefore the country is very prone to flooding. Dikes and polders have been constructed to manage the water and reduce this risk. An elaborate organisational system was set up for their maintenance: the water boards. Next to these administrative bodies, the Dutch cities of Holland often had their own policies on water management. Modern research into historical maps and archives on water management shows how an integrated policy connecting urban and water board administrations in the past has led to a safe (living) environment. In contrast, places where this integrated policy was abandoned in favour of new developments without historical knowledge are often characterized by persisting flooding and subsidence problems. This underlines the importance of knowing old policies and visions, since they still have a clear influence on the present-day landscape. Consequently, better understanding of these systems might provide solutions to future problems we face regarding amongst other climate change, soil erosion and subsidence. In this paper we present the development of a historical GIS on water systems, which is currently conducted at the Cultural Heritage Agency of the Netherlands. The focus of this paper will be on the methodology of integrating maps, archives and historical solutions into one GIS. This new integral historical landscape GIS will not only guarantee the preservation of cultural heritage in present-day dynamic environments, but can also give recommendations for climate-adaptation policies, demonstrating the importance of historical data for modern challenges. Key words: Heritage data for climate change adaptation strategies, Historical GIS, Water management. CHNT Reference: Menne Kosian and Rowin van Lanen 2019. The Importance of History for Modern Climate Adaptation Strategies. INTRODUCTION Located in north-western Europe, the Netherlands are part of the Rhine-Meuse-Scheldt-Weser delta. The majority of the country is low lying and thus prone to flooding. (Fig. 1) For centuries dikes and polders have been constructed in order to manage and contain the water and regulate the changing rivers. Around AD 1300 all the major rivers were diked in, and some of the minor rivers were dammed off. [Vos et al. 2011] An elaborate organisational system was set up for their upkeep and maintenance: the water boards. Next to the water boards, the individual cities of Holland had their own political needs, strategies and ideas, and not only for water quality and safety. These several governmental bodies sometimes even had opposite interests. During the 17th and early 18th century the Netherlands knew a period of great prosperity, the so-called Dutch Golden Age. Especially the cities in the western parts of the country, the provinces of Holland and Zeeland capitalized on this economic boom and grew incredibly. With this growth came a huge increase in energy need. For Author's address: Menne Kosian, Landscape Department, Cultural Heritage Agency of the Netherlands, Smallepad 5 3811 MG Amersfoort, the Netherlands; email: [email protected]; Rowin van Lanen, Directorate Digital, Cultural Heritage Agency of the Netherlands, Smallepad 5 3811 MG Amersfoort, the Netherlands; email: [email protected] CHNT 22, 2017 1:2 M. Kosian and R. van Lanen industrial purposes this energy mainly came from windmills, but in urbanized context peat was the main source of fuel. Peat extraction, however, causes land erosion and subsidence, and consequently increased risk of flooding. Most cities and water boards therefore had strict rules regarding extraction activities in order to keep the land safe from flooding. Fig. 1. The Netherlands as part of the north western European river delta between the Rhine, Meuse, Scheldt and Weser rivers. The light red line depicts the 50m. contour line. Below this contour is the northwest European delta. The red rectangle is the research area. In modern times the water boards are still responsible for the regional water protection policies, while the state is responsible for the larger rivers and sea barriers. (Fig. 2) However, fueled by problems like climate change, these traditional policies are changing. At first, the likelihood of flooding was conventionally met with the construction of higher and stronger dikes. Newer plans such as ‘Ruimte voor Rivieren’ (‘Space for Rivers’) and the ‘National Climate Adaptation Strategy 2016 (NAS)’ [Rijkswaterstaat 2016] promoted an adaptation of the landscape to accommodate water fluctuations. Dikes should be strengthened on the basis of a risk analysis for exceptional floods, while peak waters should be countered by temporal storage. Currently, new models are being developed to calculate flood risks instead of flood probabilities. [Bomers et al. 2018] These models take all kinds of hydrological variables into account, as well as geological and geophysical aspects, but only a very limited amount of historical data. This is best explained by the fact that these models are basically quantitative models, whereas historical data are generally more of qualitative nature, i.e. records describing the situation or event. However, as already stated, the Netherlands know a long history of water management and therefore quite some measurements have been taken throughout history. For example, relatively detailed information is available on water levels and floods in the North Sea at Katwijk, the IJ river and the water level in the boezem (the drainage of the polders) of the Rijnland water board area (mainly the area north of the current city of Delft, west of Woerden, the Haarlemmermeer and the North Sea) for July 1737 till June 1740. [Bolstra 1740] CHNT 22, 2017 Publication date: February 2019 The importance of history for modern climate adaptation 1:3 Fig. 2. The research area with the most important toponyms and the water boards. Another important source of historical information is the so called ‘Waterstaatskaarten’. From 1850 onwards the whole of the Netherlands was uniformly mapped with all data necessary for the upkeep of the elaborate water management system (e.g. polder levels, mean sea level, drainage capacity of sluices and canals etc.). These 1:50.000 scale maps were published and regularly updated from 1865 onwards and came with a complete descriptive book on polder levels, water management systems and hydrological engineering works. [Ministerie van Verkeer en Waterstaat 1983] This kind of information from historical sources does not only provide essential data for modern hydrological modelling, but also gives valuable insights into the superregional water management systems. This superregional approach also facilitates more integrated multi-disciplinary research. Allowing to assess not only problems like flooding, peak rain showers or soil subsidence in a specific region, but also integrate river water influx from other regions, alternative drainage and agricultural, urban and economic land use. To access and adequately use these historical sources we will develop a new GIS model and approach. This paper will give a first impression on the research project that will lead to such an integrated historical landscape GIS and will present some preliminary outcomes. METHODOLOGY: BASIC DATA AND GEOMETRY Most GIS databases are specifically developed for present-day situations. And although there are very good examples of historical GIS datasets, they mainly focus on one specific period. Making diachronical comparisons between numerous datasets is often challenging. For a GIS integrating water management, energy, agricultural and urbanistic landscape characteristics, the first problem to be tackled is what to use as a geographical and geometrical base map. Since the objective of the GIS is to inform modern planners and integrate historical data into modern models and processes the geometry of the GIS should comply with modern cartographical standards. Therefore the basic geometry was taken from the modern standard 1:10.000 Dutch topographical map. From this map the centre CHNT 22, 2017 Publication date: February 2019 1:4 M. Kosian and R. van Lanen line of the relevant waterways was taken as the base for the GIS geometry. To establish what the relevant waterways are, the data on water type was used as given by the ‘Planbureau voor de Leefomgeving’ (PBL Netherlands Environmental Assessment Agency) in their GIS dataset ‘Basiskaart Aquatisch: De Watertypenkaart’ (Aquatic base map of the Netherlands; map of water types). [Planbureau voor de Leefomgeving 2010] Even with this elaborate dataset creating a GIS covering the entire country will prove challenging. The majority of historical information on water management originates from the western and central parts of the Netherlands, most notably the provinces of Noord-Holland, Utrecht and Zuid-Holland. These provinces are also the areas with most water-safety related problems, soil subsidence and land-use changes (i.e. new methods for agriculture in peat meadows). In order to ensure the best data comparison and integrity our research area covers the lower central Dutch river area, basically the drainage of the old Rhine system. (Fig. 3) The boundaries of the GIS are in the west: just east of the city of Utrecht, in the north: the former Zuiderzee and IJ river, in the south: the rivers Lek and Nieuwe Maas and in the west: the North Sea. Subsequently, this area covers the present day water boards of Rijnland, Amstel, Gooi en Vecht, Delfland, Schieland en de Krimpenerwaard and De Stichtse Rijnlanden. Historical data from these water boards or their predecessors are available via their archives. Therefore we can say that the historical data coverage of the research area is the highest in the Netherlands. One of the data fields in the Aquatic base map dataset is whether a specific watercourse at present is in use as a main or a secondary drainage or has no active drainage function today.